Material Handling

Material Handling

Accidents in automatic warehouse during maintenance — how can we avoid the risk?

Risk of accidents in conventional systems: trapped in hazardous area and accidents

Automatic warehouses used in large-size material handling facilities need safety measures to avoid accident risks, such as by installing a safety guard. Two types of safety product can be used at the door of a safety gate: an interlock switch to allow the door to open after the stacker crane has stopped, and a safety plug to keep the machine stopped and to be taken into the hazardous area with the worker as a portable key. During maintenance work following an error in conventional systems, for instance, a maintenance worker first needs to switch the machine to maintenance mode, and removes the safety plug to keep the machine stopped. The worker then opens the door where the interlock switch installed and enters the hazardous area for maintenance work. In conventional systems such as described above, two potential risks are present.
Firstly, while a worker is inside the hazardous area, someone might mistakenly lock the door. If the machine is restarted, the worker inside the hazardous area gets trapped, unable to unlock the door from inside. Secondly, when the safety plug is removed in order to stop the machine, it can be tampered easily using a tool to defeat the stop function, which might result in a serious accident if the machine is restarted by someone whether intended or not.